Re: jsonb format is pessimal for toast compression

Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> Stephen Frost <sfrost(at)snowman(dot)net> writes:

>> Trying to move the header to the end just for the sake of this
>> doesn't strike me as a good solution as it'll make things quite
>> a bit more complicated.

Why is that?  How much harder would it be to add a single offset
field to the front to point to the part we're shifting to the end?
It is not all that unusual to put a directory at the end, like in
the .zip file format.

>> Is there a way we could interleave the likely-compressible user
>> data in with the header instead?
>
> Yeah, I was wondering about that too, but I don't immediately see
> how to do it without some sort of preprocessing step when we read
> the object (which'd be morally equivalent to converting a series
> of lengths into a pointer array).

That sounds far more complex and fragile than just moving the
indexes to the end.

--
Kevin Grittner
EDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company